Using infrared tomography (IRT), the broad, long term objective of the proposed research is the development of a three-dimensional tomographic reconstruction algorithm (TRA) as a means to determine the: (1) initial space-dependent temperature increase in subsurface chromophores (delta T CHR(zetu,eta,zetu,t=0)) immediately following pulsed laser exposure; and (2) depths and physical dimensions of discrete subsurface chromophores. Although our research is being shared with workers in a variety of disciplines, and pertinent to many clinical applications involving laser-induced photothermal mechanisms, the principal investigator and colleagues are particularly interested in addressing the problems associated with determination of the initial space- dependent temperature increase in subsurface chromophores in human skin in general, and port wine stain (PWS) blood vessels in particular. The project will be conducted in the combined basic research laboratories and outpatient clinic at the Beckman Laser Institute and Medical Clinic, University of California, Irvine. Design and development of the tomographic reconstruction algorithm (TRA) will be guided by studies proposed at four levels: (1) in vitro phantom collagen film model chromophore experimentation; (2) in vivo studies using the chick chorioallantoic membrane (CAM); (3) studies on the chicken comb animal model; and (4) clinical trials in PWS patients.